The pulsed columns generally comprise an upper portion equipped with one inlet of the heavy phase, namely the solid phase, and one outlet of the light phase, namely the liquid phase. The exchange takes place during the respective fall and rise of the two phases in a cylindrical central portion with a vertical axis and provided with a lining intended to favor contact between the two phases. One lower portion terminates the central portion and comprises one inlet of the light phase and one outlet of the heavy phase. The effectiveness of the transfer of a substance, such as a solute, from one phase into the other more particularly depends on the quality of the contact between the two phases. Thus, the column is equipped with a pulsation device making it possible to generate a continuous to-and-fro movement of the unit constituted by the two liquid and solid phases.
When the pulsed column is functioning, the heavy phase descends by gravity and the liquid phase rises. The linings are generally constituted by perforated plates or chicanes constituting temporary obstacles to the direct routing of the two phases. The pulsations transmitted into the mixture favor the contact between the two phases.
Generally speaking, the solid-liquid extraction dwell times need to be long since the exchange kinetics are slow. Thus, it is vital to have relatively high pulsed columns so as to obtain good efficiency. In fact, the solid phase, introduced at the top of the column, circulates by gravity by gradually moving too quickly past the various obstacles constituting by the lining inside the pulsed column.
The object of the invention is to overcome this drawback by modifying the design of the lining of the solid-liquid pulsed columns so as to ensure long dwell while observing the agitation conditions required for transfer of the solute to be extracted.